Generally, chromatography columns are used in industrial processes to purify process liquids and separate substances of interest from process liquids. Currently, chromatography columns comprise a column wall in the form of a hollow column tube, which is connected to a removable upper end plate assembly and a removable lower end plate assembly. One end plate assembly is provided with a process fluid inlet arrangement, typically comprising an inlet pipe and an inlet valve and the other end plate assembly is provided with a process fluid outlet arrangement, typically comprising an outlet pipe and an outlet valve. Each end of the column tube is usually provided in the interior of the column with a removable distribution system. These inlet and outlet distribution systems may be attached to the respective end plate assembly or the upper distribution system may be arranged to be movable towards or away from the end plate assembly.
During use, the space in the column between the distribution systems is usually filled with a chromatography medium. If necessary a retaining mesh may be provided between each distribution system and the media. The inlet distribution system is intended to distribute incoming fluid evenly over the surface of the media at the inlet end of the column while the outlet distribution system is intended to collect fluid evenly from the surface of the media at the outlet end of the column. Such a column may weigh several tons. Typically, the end plate assemblies are bolted to flanges provided at each end of the column. Alternatively, the end plate assemblies may be connected by longitudinal tie bars. Seals are usually provided between the end plates assemblies, inlet and outlet pipes, distribution systems and valves in order to prevent leakage. Columns are typically provided with legs to raise the lower end plate assembly off the ground in order to provide access to the lower end plate assembly, the inlet or outlet pipe and the valve arrangement.
A bed support is typically assembled of an outer ring, a mesh (which could be made of several layers) and for some models of columns an inner ring to which for example a valve could be fitted.
In order to manufacture the bed support of the column, mesh is generally welded to the outer ring in order for the bed support to hold the separation media in the column. The ring is usually made of stainless steel. Even though, the weld produces a good fit between the mesh and bed supports there are problems associated with welding.
The welding process has a tendency to generate a lot of heat, which changes the properties of the stainless steel material and makes it prone to corrosion. This heated stainless steel may begin to corrode, which may allow rust particles and dissolved metal ions to enter into the packing material that sits on top of the bed support. If these impurities originating from corrosion process were to enter the separation media utilized in the column, then the packing material, the separation media, may be considered useless and would need to be replaced. Further, since the welding process causes deterioration of the corrosion resistance of the stainless steel it makes the manufacturing process unreliable, and decreases the yield. The quality of the final product is poor, as the bed support once mounted in the chromatographic column will corrode leaking corrosion products into the substance, which is to be purified.
Therefore, there is a need for a new manufacturing process for assembling a mesh onto a bed support that is reliable, increases the yield and improves the quality of the final product of the bed support.